Oil shale retorting apparatus having frusto-conical passages



April 28, 1970 SAVAGE ETAL 3,509,027

OIL SHALE RETORTING APPARATUS HAVING FRUSTO-CONICAL PASSAGES Filed April 20, 196'? 3 Sheets-Sheet 1 mvzzmoRa i055 Awi/Lmas' b Y Max/u M10441 54%455 Anvil/El? A ril 28, 1970 R. H. SAVAGE Em- 3, 0

OIL SHALE BETORTING APPARATUS HAVING FRUSTO-CONICAL PASSAGES 3 Sheets-Sheet 2 Filed April 20. 1967 Z 5L lDl/VG PL A TE INVENTORS BY fol/M mil/AM ill/A62 M United States Patent O" 3,509,027 OIL SHALE RETORTING APPARATUS HAVING FRUSTO-CONICAL PASSAGES Robert Harry Savage, Downey, Calif., and John William Savage, Rte. 1, Box 107, Rifle, Colo. 81650; said John W. Savage assignor to said Robert H. Savage Filed Apr. 20, 1967, Ser. No. 632,385 1 Int. Cl. Cb 53/06, 1/04, 49/06 U.S. Cl. 202108 9 Claims ABSTRACT OF THE DISCLOSURE A retort and retorting system using one or more vessels, each having several outlets for the discharge of processed solids. Each of these outlets is communicated withthe interior of the vessel by an inverted frusto-conical passage which is shaped to bound the cone flow pattern of the solids. Process gases are introduced through the walls of the frusto-conical passages.

BACKGROUND OF THE INVENTION This invention relates to a method and apparatus for processing solid material with a counterflowing fluid. The invention has a particularly valuable application in the retorting of oil shale.

Generally the exploitation of oil shale has envisioned systems employing a retort for processing crushed shale. For retorts of large diameter, the crushed shale is usually of relatively uniform particle size to accommodate the heat transfer method used in extracting hydrocarbons from the shale. This heat transfer process requires a mass or bulk movement of crushed shale through a processing zone in the retort. Mass or bulk movement is effected when substantially vertical movement of individual shale particles, without an appreciable horizontal component of particle motion, occurs. Hot gases are passed through the bed of descending shale in countercurrent fashion, that is, in a direction opposed to the mass movement of the shale. In order to avoid the creation of voids or channels in the moving shale, in which the hot gases would preferentially flow, the shale is ground to uniform size. In addition, uniform sizing of shale particles is required to avoid agglomeration of particles which results in clogging of passages between individual pieces of shale and channeling adversely affecting heat transfer and the efliciency of the retorting process.

However, maintaining mass flow of particles without agglomeration and the uniform countercurrent contacting of a gas stream with such a bed without channeling is difficult, especially in large-sized retorts. In short, despite the efforts to avoid agglomeration and channeling in mass flow systems, it has been found that the counterflowing gas develops preferred flow patterns which bypass large amounts of shale.

U.S. Patent 2,661,325 to Harry K. Savage describes an oil shale processing system in which oil shale descends through a processing zone with both lateral and vertical components of motion. Lateral movement is accomplished through the phenomenon known as cone flow. Cone flow is developed in a system where the outlet of a container in which particled material descends is small relative to the lateral dimensions of the container. Thus, in a retort when the lateral dimensions reasonably exceed the effective dimensions of its outlet or outlets, cone flow can develope. The angle described by the cone fiow varies with the solid material. For oil shale, the angle between the horizontal and one side of the cone is approximately 70 degrees. The horizontal component of cone flow produces shearing stresses which increase in magnitude as shale ap'-' proaches the retorts outlet. This horizontal motion pro- 3,509,027 Patented Apr. 28, 1970 ice duces a mixing of the descending shale which overcomes channeling and promotes efficient heat transfer with counterflowing gases.

The savage patent indicates that sequential cone flow in a retort system having a plurality of outlets can be used to create lateral movement of shale well up into the bed or processing zone. When a plurality of open outlets is used in a retort, cone flow terminates when two or more cones of flow intersect. Sequential withdrawal avoids these lines of intersection to produce cone flow in a much larger volume of shale than would otherwise be possible with all of the retorts outlets simultaneously open to shale flow.

In a retorting system employing cone flow, shale accumulates between the outlets of the retort. This is because the outlets are spaced apart and cone flow does not exist in regions proximate the bottom of the retort, that is, in those areas close to the outlets between zones of cone fiow. These dead spaces create wasteful areas of shale deposit. In addition, efiicient introduction of heating gas should be ccomplished proximate the outlets of the retort. Accumulation of shale in dead spaces reduces the number of locations available for introduction of the heating gas.

SUMMARY OF THE INVENTION The instant invention provides an improved material processing retort and process utilizing the cone flow concept and is characterized by the absence of dead space in the retort.

The retort of the instant invention includes an enclosed vessel having an interior or processing zone for processing solid, partical material. The vessel has a plurality of spaced-apart outlets for the discharge of processed solids. A plurality of inverted frustoconical passages communicates these outlets with the vessels interior. Each of the cones diverges from an associated outlet upwardly into the interior. The frusto-conical passages are shaped to bound the cone flow developed by freely flowing, particled solid material. For oil shale, the included angle of each cone is approximately 40 degrees. In addition, means for introducing solid material for gravity flow through the process zone are provided. Means are provided for introducing a hot process fluid into the retort in countercurrent flow with descending solid material. Means are also included for withdrawing the heating fluid from the process zone after it has heated the descending solid material.

In a preferred form of the instant invention, the heating fluid is introduced through apertures for inlets in the walls of the frusto-conical passages. Means are also provided to sequentially withdraw the solid material from the vessel to increase cone flow above the terminus of the frusto-conical passages.

A preferred form of the instant invention provides an apparatus and process for the recovery of organic products from oil shale. A retort such as that just described is used. Fresh shale is introduced into the top of the retort where it is allowed to descend by gravity through a retorting zone for retorting and subsequent discharge through the inverted frusto-conical passages and the retorts outlets. The processed shale thus discharged is introduced into a furnace where it is combined with air for burning its residual coke to produce heat energy. The volatile products produced in the retorting process are withdrawn from the retort and passed through a separator preferably in the form of an electrostatic precipitator. The volatiles are then separated into a product gas and product oil. Some of the product gas is separated for recycling. The recycled gas is heated by the products of combustion of the furnace. After it is heated, the recycled gas is introduced into the retort in countercurrent flow with descending shale to retort the shalt.

The inverted frusto-conical passages defined by the invention can be used in multiple bed oil shale processing systems. One such system includes a retort having communicating retort, combustion and cooling zones. Each zone has a plurality of the inverted frusto-conical passages previously described. Means are included for introducing fresh shale into the retorting zone for retorting and producing volatile organic products. Retorted shale passes into the combustion zone where it is combined with air for the burning of its residual coke. Spent shale from the combustion zone is passed into the cooling zone and subsequently out of the retort. A condenser or precipitator separates the volatiles into a product oil and a product gas. Preferably a portion of the product gas is diverted to form recycled gas .which is directed through inlets in the frusto-conical passages of the retorting zone for use in the retorting process. Products of combustion from the combustion zone are directed through a heat exchanger to heat the recycle gas before its introduction into the retorting zone. After passing through the heat exchanger, the products of combustion are separated into two streams and combined with air. One of the streams is directed into the combustion zone through inlets in the frusto-conical passages where its residual heat is used to increase the etficiency of the combustion process. The second stream is introduced into the cooling zone. Gas from the cooling zone is mixed with the combustion products leaving the combustion zone for introduction into the heat exchanger.

Among the advantages of the invention is the elimination of dead spaces between outlets of a retort in which particled solids undergo cone flow. The frusto-conical passages prevent the accumulation of solid materials between the retorts outlets resulting in the elimination of areas of non-flowing solids and the enhancement of solid processing. The passages may also be used for the introduction of a heating fluid into the retorts processing zone. Because of the cone flow of the solids in the retort, there is considerable lateral mixing of individual solid particles. Introducing the processing fluids into these solids through the passages results in excellent solid-gas contact with a substantial reduction in the probability of material channeling and shale clinkering. Lateral mixing in shale oil retortingsystems substantially reduces the requirement for uniform shale sizing because the problems of channeling and agglomeration are overcome. Without the re quirement for uniform crushing or the separate retorting of different'size shales, the economy of a shale processing system is materially enhanced. Cone flow retorting systems eliminate the requirement for expensive mechanical mixing devices which would otherwise be necessary in systems for processing shale with varied particle sizes. Because of the mixing qualities resulting from cone flow, scale-up problems are avoided and large retorts can be used without encountering channeling, clinkering or using uniform sized shale particles.

Moreover, shale often contains residual products, other than the organic products recovered in the retorting process, such as aluminum-bearing minerals. The efliciency and ease of recovery of these products are improved when the original shale size is preserved. Cone flow retorting preserves the original shale size and avoids the formation of fines, and is thus especially suitable for use with shales containing residual products.

Increased regions of horizontal as well as vertical mixing are possible when sequential withdrawal of solids from the retort is used because cone flow is induced well above the cone flow region experienced when all the outlets are open to solid flow. Sequencing the outlets used for solid withdrawal, then, can be used to produce mixing in any part of the retort. This feature, combined with the elimination of dead space and the efiicient introduction of process fluids through the walls of the frustoconical passages, further diminishes the probability of clinkering and channeling.

In retorting rich clinkering oil shales, it is desirable to have a number of retorting zones for retorting the shale at difierent temperatures. The retort and process of the invention are readily adapted tosuch multiple bed retorts.

These and other features, aspects and advantages of the instant invention will become more apparent from the following description, appended claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic diagram showing flow patterns of particled solids descending through a container and out through a plurality of passages;

FIGURE 2 is a view taken along line 22 of FIG- URE 1;

FIGURE 3 is a view taken along line 3-3 of FIG- URE 1;

FIGURE 4 is a view taken along line 44 of FIGURE 3, showing a modification;

FIGURE 5 is a perspective view in half cross section of one embodiment of the instant invention;

FIGURE 6 is a schematic illustration showing an oil shale retorting system of the instant invention; and

FIGURE 7 is a schematic illustration showing another oil shale retorting system of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to FIGURES 1, 2 and 3, a schematic illustration of a container having a plurality of outlets is shown. Typical cone flow patterns for solid material descending through the container and out through the outlets are shown in phantom. When material is descending through the container with all the outlets open, fully established cone flow below plane 33 will occur. During this flow regime, the flow between plane 2-2 and plane 33 is transitional. Transistional flow is the sum of both cone fiow and mass flow with cone flow only in those parts of the container having non-intersecting phantom lines. Above plane 22 only mass or bulk flow is present. FIGURE 2 is illustrative of the limit for cone flow when all the outlets are open. The circular phantom lines indicate the cone flow pattern at plane 22 for each of the outlets when all of the other outlets are closed. It is possible to have fully established cone flow at plane 22, however, when more than one outlet is open. For example, with outlets 20, 22 and 24 open, and with the remaining outlets closed, cone flow between these outlets and plane 22 is possible. Similarly, with only outlets 22 and 26 open, cone flow between plane 22 and these outlets occurs. With center outlet 10 open and the remaining outlets closed, cone flow exists within the confines bounded by the phantom lines below plane 1212 to outlet 10. The closing of all the outlets except outlet 16 establishes cone flow between plane 14 and the outlet which is represented by the phantom line extending between outlet 16, the wall of the container and plane 1414. In like manner cone flow is established between plane 1414 and outlet 18 when only this outlet is open.

FIGURE 4 more clearly depicts the transition zone between planes 22 and 33 with all the outlets open. Cone flow will exist in the transition zone for outlet 10 until interference occurs with the cone flow of other outlets or the side of the container. Line 28 represents the intersection line between cone flow to outlets 16 and 22 FIGURE 3) while line 30 represents a similar interference between the cone flows of outlets 18 and 26. These lines, and hence cone flow, terminate at the wall of the container. -Line 32 represents the locus of points of intersecting cone how for outlets 16 and 22 which terminates abruptly at its intersection with the cone flow of outlet 10. In like manner, line 34 is determined by intersecting cone flow from outlets 10, 18 and 26, above lines 28 through 34 only mass flow exists.

FIGURE 5 depicts one embodiment of the retort of the instant invention. Retort 40 comprises an enclosure 42 having a shale inlet 44 disposed at its top in position to deposit shale into retorting zone or bed 46. The shale inlet is a manifold to evenly distribute shale in the retorting zone. A plurality of inverted frusto-conical passages are disposed in the interior of the retort 40 between retorting zone 46 and the retorts outlets. Each frustoconical passage communicates one of the retorts outlets with the retorting zone. Outlet 48 of frusto-conical passage 50 is disposed in base plate 52 in shale communication with the interior of the passage; In like manner, outlets 54 and 56 are disposed in base plate 52 in shale communication with their respective frusto-conical passages 58 and 60. The walls of the frusto-conical passages are formed of a material which is suitable to withstand retorting temperatures. Each wall of the frusto-conical passages has a plurality of processing gas inlets which are indicated by reference numeral 62. Preferably, the inlets are large in number to insure even distribution of processing gas in retorting zone 46 which results in a very high incidence of process gas-shale contact. Process fluid is introduced into distribution space 64 through conduit 66. Conduit 66 has a plurality of openings 68 along its length for distributing hot processing gases into space 64 and, subsequently, through apertures 62 into retorting zone 46. Retorting zone floor 70 forms the upper boundary for distribution space 64. The lower confines of space 64 is formed by closure plate 72. The lateral confines of distribution space 64 are provided by the enclosure 42.

Preferably, means are provided for sequencing the flow of shale through each of the frusto-conical passages. In the embodiment shown in FIGURE 5, sequential fiow is accomplished through a sliding plate 74 which has a plurality of staggered shale passages corresponding in number to the number of frusto-conical passages. Shale passage 76 communicates frusto-conical passage 50 with outlet 48 when plate 74 is positioned to match the passage with the outlet. In like manner, shale passage 78 in plate 74 cooperates with frusto-conical passage 58 and its outlet 54 and shale passage 80 cooperates with frusto-conical passage 60 and outlet 56 upon the appropriate positioning of sliding plate 74 with respect to each of the frustoconical passages. The shale passages in plate 74 can be staggered to accommodate the retorts dimensions and the grade of shale processed. Staggering, as was discussed previously promotes cone flow well into processing zone 46 which is important for proper shale-process gas contact and the avoidance of channeling. Other means, such as a revolving circular plate, may be used to provide staggered flow from the retorting zone. To maximize the volume within retorting zone 46 which undergoes cone flow, the upper terminus of the inverted frusto-conical passages should be no lower than the point of contact between adjoining passages. If desired, filler structure above floor 70 defined by the lines of intersection of cone flow of each frusto-conical passage can be employed. In addition, the use of frusto-conical passages throughout the breadth of floor 70 enhances shale retorting. Thus, frustoconical passages 82 and 84 are provided.

Spent or retorted shale passing through the outlets is collected in bin 86 for discharge through spent shale opening 88. Process gas and the organic products of the retorting process are exhausted from retorting zone 46 through pipe 90.

The included angle between the sides of the frustoconical passages is dictated by the material being processed. As was previously mentioned, the included angle for cone fiow varies with different materials. In oil shale the included angle is approximately 40 degrees.

The Concepts discussed with reference to FIGURE 4 can be employed in the embodiment shown in FIGURE 5. A modification of retort 40 provides for the filling of the space above fioor 70 which is not experiencing cone flow when all the frusto-conical passage outlets are open. Filling structure geometrically determined by the extension of the walls of each of the passages until they intersect with the extension of an adjoining wall is preferred. This structure is useful in avoiding a dead space above floor 70 in which shale would otherwise accumulate. Because of the geometry involved, the filling structure can be approximated to fill the dead spaces. If desired, process gas can be introduced into the retorting zone 4'6 through gas inlets in the filling structure to augment the gas introduced through the frusto-conical passages.

FIGURE 6 is a schematic depiction of a preferred retorting system and process for the recovery of organic products from oil shale. Retort 40 is identical with the retort described with reference to FIGURE 5. Furnace 100 is in communication with bin 86 of retort 40. Separator 102, through pipe or line 90, is in communication with processing zone 46 for the separation of the organic products retorted in retort 40- into a product oil and a product gas. Preferably, separator 102 is an electrostatic precipitator. Compressor or blower 104 communicates recycle gas, which is a diverted portion of the product gas, with furnace 100. Heat exchanger 106 within furnace 100 is used to increase the thermal energy of the recycle gas by heat exchange with the products of combustion emanating from burning retorted shale. The heat exchanger is closed to the products of combustion of furnace 100 to avoid contamination of recycle gas. Thus heat exchange between the recycle gas and the combustion products is indirect. Heat exchanger 106 is in communication with retorting zone 46 through conduit 66 and the apertures in frusto-conical passages 50, 58 and 60.

Fresh shale is introduced into retorting zone 46 through shale inlet 44 where it is retorted by the heated recycle gas from heat exchanger 106. Shale within the retorting zone experiences cone flow as it descends for discharge through the frusto-conical passages. Organic products produced by the retorting process pass through line to precipitator 102 where they are separated into a product gas and a product oil. The product oil is removed from the system While the product gas is diverted to form two streams. One stream is taken from the system while the other is recycled. The recycled gas is compressed in blower 104 and introduced into heat exchanger 106 of furnace 100. Furnace receives retorted shale from collection bin 86. The retorted shale contains coke which is burned with air in furnace 100 to generate products of combustion. The products of combustion pass in indirect heat exchange relationship with recycle gas in heat exchanger 106. The heated recycle gas, then, becomes the process gas which is introduced into retorting zone 46 through the frusto-conical passages. The process gas passes in countercurrent flow relationship with shale within the retorting zone.

FIGURE 7 depicts schematically a multiple bed or zone retort together with attendant organic product recovery apparatus. The retort has a retorting zone 122, a combustion zone 124 and a cooling zone 126. Each zone has a plurality of frusto-conical passages which were described with reference to the previous embodiments. Thus, retorting zone 122 has frusto-conical passages 128 which communicate the zone with combustion zone 124. Combustion zone 124, in turn, has a plurality of frusto-conical passages 130 communicating it with cooling zone 126. Spent shale from cooling zone 126 is discharged through frusto-conical passages 132.

Organic products from retorting zone 122 pass through conduit 134 to electrostatic precipitator 136. The precipitator separates these products into product oil and product gas. Blower or compressor 138 is in communication with precipitator 136 through conduit 140. The product gas compressed in blower 138 passes through conduit 142. Conduit 144 diverts a portion of the product gas from conduit 142 to form recycle gas. Heat exchanger 146 is in communication With conduit 144 and conduit 148. Conduit 148 communicates retorting zone 122,

through apertures in frusto-conical passages 128, with heat exchanger 146.

Conduit 150 communicates combustion zone 124 with heat exchanger 146- Preferably, heat exchanger 146 is of the type where the recycle gas and products of combustion from combustion zone 124 do not mix. Blower or compressor 152 compresses combustion products which have passed through heat exchanger 146 and conduit 154. Conduit 156 receives these combustion products from blower 152. Conduit 158 is in communication with conduit 156 as are air conduit 160 and conduit 162. Cooler 164 is in communication with conduit 160 and cooling zone 126 through conduit 166 and apertures in frusto-conical passages 132. Gases from cooling zone 126 are introduced intoconduit 150 through line 167.

Spent shale is discharged from the cooling zone through shale outlet 168 while fresh shale is introduced through shale inlet 170 into the retorting zone. Sequential withdrawal of shale, as discussed with reference to FIGURE 5, from each of the zones is desirable.

Fresh shale introduced through shale inlet 170- is retorted in retorting zone 122. Organic products from the retorting zone are separated into a product oil and a product gas in precipitator 136. The product gas is compressed in blower 138 after which a portion of it is diverted from conduit 142 in the form of recycle gas. The recycled gas passes in indirect heat exchange in heat exchanger 146 with the products of combustion from combustion zone 124 and the heated gases passing (from cooling zone 126. After being heated in heat exchanger 148, the recycle gas is introduced into retorting zone 122 through the walls of inverted frusto-conical passages. The recycle gas then passes in countercurrent flow with shale descending, under the influence of cone flow, through the retorting zone to retort the shale.

Retorted shale passes into combustion zone 124 Where its residual coke is burned with counterflowing air introduced through air conduit 160, conduit 158 and the walls of inverted frusto-conical passages 130. The shale within combustion zone 124 also experiences cone flow. Recycled combustion products are introduced into zone 124 to increase the efiiciency of the combustion process. The products of combustion from the combustion zone, with the gases from cooling zone 126, heat the recycle gas in heat exchanger 146. These gases are compressed in blower 152 after which they are combined with air to form two streams. One stream is introduced into combustion zone 124 as described. The second stream passes through cooler 164 into cooling zone 126.

Shale discharged from combustion zone 124 into cooling zone 126, through frusto-conical passages 130, is cooled by air and combustion products introduced through the walls of frusto-conical passages 132. The cooling process is accomplished by the counter-current flow of these gases with shale descending in cone fio-w through the cooling zone. The thus heated gases are then combined with combustion products for introduction to heat exchanger 146.

The subject invention has been described with reference to certain preferred embodiments. The spirit and scope of the appended claims should not, however, be limited to this description.

What is claimed is:

1. A retort for processing oil shale comprising:

an enclosed vessel having an interior defining an oil shale processing zone and a plurality of spaced-apart outlets at the bottom of the zone for the discharge of spent oil shale from the zone, thespacing between outlets being such that cone flow of oil shale will develop in the vessel;

means for introducing fresh oil shale into the vessel such that the fresh oil shale is capable of descending by gravity through the processing zone;

wall means in the vessel defining a plurality of inverted frusto-conical passages, each passage having a circular cross-section and communicating one of the vessels outlets with the processing zone, the included angle of each of the passages being substantially 40 to conform to the cone flow angle of oil shale;

means for introducing a fluid into the vessel through the wall means defining the frusto-conical passages such that countercurrent flow is capable of being effected between the oil shale descending through the processing zone and the fluid; and

means for withdrawing the fluid from the zone after it has passed through the oil shale.

2. The retort claimed in claim 1 wherein the fluid introduction means include a plurality of fluid inlets in each of the frusto-conical passages for the introduction of fluid into the processing zone.

3. The retort claimed in claim 2 including means associated with the outlets of the vessel for sequentially withdrawing spent oil shale therefrom to increase the cone flow of oil shale above the frusto-conical passage means.

4. An oil shale processing system comprising:

an enclosed vessel having an interior defining an oil shale retorting zone and a plurality of spaced-apart outlets for the discharge of retorted shale from the zone, the spacing between outlets being such that cone flow of oil shale will develop in the vessel;

means for introducing fresh shale into the retorting zone such that fresh oil shale is capable of descending by gravity through the retorting zone;

wall means in the vessel defining a plurality of inverted frusto-conical passages, each passage having a circular cross-section communicating one of the vessels outlets with the retorting zone, the included angle of each of the passages being substantially 40 to conform to the cone flow pattern of the oil shale;

a separator in communication with the retorting zone for separating organic products produced from the retorting of the oil shale into a liquid product and a gas product;

a furnace in shale communication with the vessels outlets for burning coke remaining in the retorted shale;

means for heating a portion of the gas product with the products of combustion of the coke; and

means for introducing the heated portion of the gas product into the retorting zone in countercurrent flow with shale descending through the zone through the wall means defining the frusto-conical passages.

5. The oil shale processing system claimed in claim 4 wherein:

the heating means includes means for indirect heat exchange between the products of combustion of the coke and the portion of the gas product; and

the inverted fmsto-conical passages have a plurality of apertures in their walls, the heated gas product introduction means including the apertures.-

6. The oil shale processing system claimed in claim 5 including means associated with the outlets of the vessel for sequentially withdrawing processed shale therefrom to increase the cone flow of shale above the frusto-conical passages.

7. An oil shale processing system comprising:

a shale retort including a retorting zone, a combustion zone below the retorting zone and a cooling zone below the combustion zone, the retorting zone having a plurality of spaced apart outlets at the bottom of the zone for the discharge of shale into the combustion zone, the combustion zone having a plurality of spaced-apart outlets at the bottomof the zone for the discharge of shale into the cooling zone and the cooling zone having a plurality of spaced-apart outlets at the bottom of the zone for the discharge of shale from the retort, each zone including wall means defining a plurality of inverted frusto-conical passages having a circular cross-section in communication with the associated zones outlets, each of the passages in all the zones having an included angle of substantially 40 to conform to the cone flow pattern of the shale, the spacing between outlets in each of the zones being such that cone flow of oil shale Will develop in each of the zones;

means for introducing fresh shale into the retorting zone;

a separator in communication with the retorting zone for separating organic products from the oil shale retorted therein into a liquid product and a gas product;

means for introducing a portion of the gas product into the retorting zone for retorting shale therein through apertures in such zones frusto-conical passages in counter-current flow with shale descending through the zone;

means for introducing air into the combustion zone to burn coke in the shale to produce combustion products; and

means for producing heat exchange between the combustion products and shale in the retorting zone.

8. The oil shale processing system claimed in claim 9 wherein:

the heat exchange means includes means for indirect heat exchange between the combustion products and the portion of the gas product which is introduced into the retorting zone.

9. The oil shale processing system claimed in claim 8 including:

a first compressor for the product gas;

a second compressor for the combustion products;

means for recycling a portion of the combustion products into the combustion zone through the apertures in such zones frustoconical passages;

means for introducing a portion of the combustion products and air into the cooling zone through apertures in such zones frusto-conical passages;

means for exhausting the air and combustion products from the cooling zone and into the combustion products from the combustion zone; and

means assoicated with the outlets of the retorting, combustion and cooling zones for sequentially withdrawing shale therefrom to increase the cone flow of shale above the frusto-conical passages of each zone.

References Cited UNITED STATES PATENTS 3,074,777 1/ 1963 Cortes. 2,131,702 9/1938 Berry 201l5 XR 2,661,325 12/1953 Savage 20134 XR 3,224,954 12/1965 Schlinger et al. 20811 3,349,022 10/1967 Mitchell et al. 20134 XR 3,384,569 5/1968 Peet 201-34 XR NORMAN YUDKOFF, Primary Examiner DAVID EDWARDS, Assistant Examiner US. Cl. X.R.

P0405) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 509,027 Dated April 28, 1970 Inventor(s) R. H. Savage et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' In the specification: Column 2 line 4, "savage" should be --Savage--; line 21, "ccomplished" should be -accomplished--; line 33, "partical" should be --particled--; line 49, "for" should be --or--; line 72, "shalt" should be---shale--.

In the claims: Claim 8, column 9, line 21, "9" should be SI'GNE MQ "WES Atteat:

Edward M. Fletcher, In an m Comisaionor 0t mums 

